Field of the Invention
The present invention relates to a bicomponent nonwoven fabric having an improved strength and air permeability and manufacturing method thereof, and more particularly to a bicomponent nonwoven fabric having an improved strength and air permeability, in which the nonwoven fabric has an improved strength together with an improved air permeability while maintaining a former physical property of the prior nonwoven fabric made of poly trimethyleneterephthalate which has proper durability and softness to be required as a multipurpose sheet and can be produced economically, but has a drawback that its strength and air permeability is unsatisfied, and the method for manufacturing the nonwoven fabric having improved air permeability.
Description of the Prior Art
It is common method to defoliate the weeds by spraying herbicide or to root up it with manual labor as weed-proofing or weeding. However, the method of using herbicide is not preferable since it contaminates the soil or kills a microorganism at the soil which will be beneficial on the growth of plants, so that it can be result in devastation of the soil. Therefore, to solve such conventional problem, the nonwoven fabric has been used to inhibit growth of the weed by inhibiting photosynthesis. Particularly, with covering the soil of agricultural land planted with various crops with nonwoven fabric, while suppressing the growth of weeds, the air is permeated and the soil is warmed so that the growth of crops can be facilitated. Therefore, the sheet which is configured to fit the above object is widely used in agriculture. As such nonwoven fabric for agriculture, a polyolefin-based, especially a polypropylene-based spunbond nonwoven fabric considering the sides of economy as a raw material has been proposed and has been used. More specifically, the said agricultural nonwoven fabric, for example, nonwoven fabric which is constructed by using a synthetic fiber filament yarn made of a polypropylene resin is provided which one side of the nonwoven fabric is partially thermocompression bonding embossing process or a non-woven fabric is produced with free embossing.
For example, Korean patent early publication 2002-36636 describes, with the title of “nonwoven fabric for agriculture”, nonwoven fabric which synthetic fiber filament yarn of 2-3 denier is arranged with the density of 55˜65 g/m2 smoothly, and then heat-pressed with a roller press to be embossed on one or both sides. These nonwoven fabrics for agriculture have a relatively good mechanical properties and its handling is easy. Also, these nonwoven fabrics have effects that the contact area with air becomes large by concave-convex parts of embossing so that the permeation of air is seamlessly. However, these nonwoven fabric thicken not to achieve an optimal air flow, and to increase the shielding degree of light, so that the corps take the rootlet into these nonwoven fabric due to misconception as soil and then the corps is withered when dry whether. Therefore, it is necessary a solution for this problem and various methods have been proposed to solve it. Such as the pre-mentioned description, the approach for improving the nonwoven fabric for agriculture relates, for example physical properties of nonwoven fabric, since the conventionally proposed nonwoven fabric for agriculture has drawback that its thick is excess and an air flow is not smooth, and a content of moisture is also excess so that there is a problem that it is difficult to achieve the original object as an inhibition of growth of weed.
But, the conventional nonwoven fabric for agriculture has a drawback that its strength and resistance is insufficient to use as an agricultural usage, although the conventional nonwoven fabric for agriculture has economical advantage since the polypropylene made of it can be produced at low cost.
On the other hand, as those having good resistance, polytrimethylene terephthalate (PTT) had been provided with the nonwoven fabric and synthetic fibers of various kinds. For example, Korean Patent Application No. 2002-0049047 describes a preparing method of polytrimethylene terephthalate staple fiber which comprises a step of (a) supplying polytrimethylene terephthalate, (b) spinning melted polytrimethylene terephthalate at a temperature of 245-285° C. to a filament, (c) quick quenching the filament, (d) extending the quenched filament, (e) winding the extended filament with 8 to 30 winding orders/inches (3 to 12 winding orders/cm) by using a mechanical winder, (f) relaxing the winded filament at a temperature of 50-120° C., and (g) cutting the relaxed filament with a staple fiber of a length of 0.2 to 6 inches (about 0.5 to 15 cm). Also, Korean Patent Application No. 2003-0070138 describes a polyester-based latent-crimping conjugated fiber and method for preparing the same. Japanese patent publication No. 2001-146671 describes a long fiber nonwoven fabric, Japanese patent publication No. 2003-306863 describes a polyester filament nonwoven fabric and a separation membrane using the same, and Japanese patent publication No. 2002-180366 describes a filament nonwoven fabric having excellent formability.
But, the prior art such as the said one never describes and suggests for a nonwoven fabric and producing method thereof which has a physical property suitable for the nonwoven fabric for agriculture while it has air permeability above a desired level as an economical nonwoven fabric by using PTT. Therefore, it is acutely needed to provide for a nonwoven fabric having air permeability above a desired level, while it keeps a physical property of PPT nonwoven fabric according to the prior art, so that the present inventors invented the a nonwoven fabric having an improved air permeability and filed it with the patent application.
However, the present inventors recognized that the PTT nonwoven fabric according to said patent application still has a drawback of a weak strength even though its softness and air permeability are excellent, and tried the various method for the spun condition and procedure to improve the said drawback, and, as a result, achieved the present invention.